Work holder for form tools



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ATTORNEYJ Patented May 5, 1942 WORK HOLDER FOR FORM TOOLS John Edgar,Rockford, Ill., assignor to Barber- Colman Company, Rockford, 111., acorporation of Illinois Original application September 28, 1934, SerialNo. 745,914, now Patent No. 2,181,396, dated November 28, 1939. Dividedand this application March 18, 1939, Serial No. 262,595

10 Claims.

This invention relates to mechanism embodying novel work supportingmeans which is operable in conjunction with grinding means and means forguiding a tool or other device in straight, curved and modified pathsparticularly adapted for employment in the manufacture of form tools.This application is a division of my copending application Serial No.745,914, filed September 28, 1934, now Patent No. 2,181,396,

issued November 28, 1939.

There are two principal methods commonly used in the manufacture of formtools, the older of which is the so-called master or fly-tool method. Toproduce a form tool by this method, it is necessary to make, first, amaster or fly-tool which possesses the shape that is desired to beproduced by the form tool, but since this fly-tool is made from a pieceof unhardened metal and is hardened after being properly shaped, anyhardening distortion must be removed by a manual process such asstoning. This method has many disadvantageous features besides beingcostly.

In view of this, another method has been advanced whereby form tools areground from hardened pieces of metal by means of abrasive wheels shapedto the proper contour. To correctly shape such an abrasive wheel it hasbeen the custom to employ a templet to which the wheel was trued, theform of the templet not being a, duplicate of the form desired butcorresponding to the form desired as corrected to compensate for theclearance angle with which the tool is made, undercut and side clearanceor any of them as may be desired on form tools for making straight gashor spiral gash cutters. It results, therefore, as will be more fullydescribed hereinafter, that to make a form tool adapted to produce acircular section it is necessary that the contour of the abrasive wheelused be elliptical, if end clearance alone is to be compensated for, andthe contour of the abrasive wheel must be further modified to compensatefor the other factors. These features of the invention are coveredbroadly in the parent application aforesaid.

An object of the invention is to providea novel work holder in a machinewhich embodies cooperating means for producing plain and modifiedcontours on a grinding wheel, as in compensating for such factors asside clearance, end clearance spiral angle and undercut, which workholder is adapted to support a form tool blank in various positions ofadjustment as determined by the contour of the grinding wheel and itsproper working relationship to the tool blank.

A further object is to provide a novel work holding device operable inconjunction with an abrasive wheel trued by a dressing mechanism toprovide a desired contour on a form tool.

Another object of the invention is to provide, in a machine of thisnature having an arbor for supporting a grinding wheel, a supportmovable transversely of said arbor, means for adjusting the height ofsaid arbor above said support, and means on one end of said support fordressing a wheel on said arbor, new and improved means on the other endof said support for adjustably supporting a work piece for propercooperation with the grinding wheel.

Further objects and advantages of the invention will become apparent asthe description proceeds.

In the drawings:

Figure 1 is a front elevation of a machine embodying the preferred formof the invention.

Fig. 1 is a diagrammatic view of a form tool and a grinding wheeladapted to move at a clearance angle with the plane perpendicular to thecutting surface of the tool.

Fig. 2 is a side elevation looking at the lefthand side of Fig. 1.

Fig. 3 is a fragmental section through the table, work support and toolsupport, taken in the plane of line 3-3 of Fig. 2.

Fig. 4 is a view along the line 4-4 of Fig. 3.

Fig. 5 is a fragmentary plan view of the undercut control shown alongthe line 55 of Fig. 3.

Fig. 6 is a front elevation of the mechanism for mounting the toolblank.

Fig. 7 is a plan view thereof.

Fig. 8 is a vertical section along the line 8-8 of Fig. 7.

Fig. 9 is a section along the inclined line 9-9 of Fig. 6. 1

Fig. 10 is a section along the line |0-l0 of Fi 8.

While my invention is susceptible of embodiment in many different forms,I have shown in the drawings and will herein describe in detail one suchembodiment, with the understanding that the present disclosure is to beconsidered as an exemplification of the principles of the invention andis not intended to limit the invention to the embodiment illustrated.The scope of the invention will be pointed out in the appended claims.

As illustrated in the drawings, an exemplary form of a grinding machine,having a work holder embodying the invention incorporated therein,comprises a supporting bed or base I for a column 2 formed integrallytherewith and extending upwardly from the rear portion thereof. Aspindle head 3 is slidably mounted on the column and has an arbor orspindle 4 rotatably mounted thereon and extending forwardly from theface of the column and over a platen or table 6 which is movabletransversely of the spindle above the knee portion 8 of the machinebase.

' Preferably a saddle l is interposed between the (Figs. 1 and 2) whichhand wheel drives through 7 amicrometer device (designated generally asI1), and suitable gearing intermediate said micrometer device and thespindle head (not shown). The micrometer-device may be of any suitableform and preferably is of the type shown .in my Patent No. 1,760,932,issued June 3, 1930.

The construction-of themachine thus far described (with the exception ofthe micrometer device 1'!) is well known to those skilled in the .art,the spindle 4 being generally driven from a motor l8 in the base of themachine by means of a :belt H), which belt engages a pulley 2i) on thespindle shaft and suitable idler pulleys 2i andZ-Z for permittingvertical adjustment of the head on the column.

An exemplary use of a work holder embodying the invention is inconnection with a machine having a dressing mechanism A mounted on oneend of a table 6. The work or tool holder B is carried by a work support23 which is slidably mounted on the left-hand portion of the table.

Hence, manipulation of the hand wheel l2 to move the table 6 moves adressing tool 124 into transversely of the grinding wheel axisfor'grinding the blank to the contour which has been formed on the wheelW by the dressing tool.

When grinding form tools, it is necessary to make allowance not only forthe end clearance angle to which the tool is ground, but in addition andout of operative relation to the grinding I wheel W and, when thedressing tool has been moved into an inoperative position, reciproeatesv.a tool blank 25 mounted in :the work holder B it is sometimesdesirable when grinding straight 4 gash tools to provide for undercut orside-clearance or both and when grinding spiral gash tools to providefor the spiral, for undercut and for side clearance. The presentadaptation -of the device A so that the conjoint use thereof with thegrinding wheel W will cause the tool blank 25 to be formed with thedesired end clearance angle, side clearance, undercut and spiral angle.The work holder B will be more fully described hereinafter. Attentionwill first be directed to the dressing mechanism generally designated A.

The followingdescription of the dressing mechanism, its associated partsand the operation thereof with respect to the grinding wheel will beabbreviated to provide a condensed version of the more completedescription thereof found in my said copending application.

The same reference numerals are used in both sets of drawings.

.invention contemplates that the work holder B Y I will be adjustable incorrelation with the dressing In Fig. 1 the form tool 2'5 is showndiagrammatically in operative relation with a grinding wheel, the toolbeing presented to the grinding wheel to provide the tool with an endclearance of angle a. It will be apparent that if the dimension xrepresents the depth or radius of the cut desired to be reproduced bythe tool, it will be necessary to make the depth y measuredperpendicular to the clearance end of the tool slightly less than thedepth it because of the angular position of the tool during grinding,the dimension y being equal to .r multiplied by the cosine of the anglea. In other words, the contour to be ground on the .tool will be that ofan ellipse which ellipse is the projection on a vertical plane of theinclined semi-circle of radius a: which defines the cutting edge of thetool. Thus, the angle a is a clearance angle. A clearance angle may bedefined as the angle of recession of the surface of a tool back of itscutting edge relative to a line through said edge extending in thedirection of movement of the tool relative to ='the work. If therecession is .on the end of the tool, as in the present instance, it hasend clearance; if on the side, it has side clearance.

The mechanism by which the operative movements of the dressing tool 24are controlled includes a holder 26 for the dressing tool '24 arrangedior free movement in a vertical plane. A head mounted for movement on anaxis inclined at the end clearance angle with the horizontal has aconnection with the head such that when the head is turned on itsinclined axis, the tool h lder 26 will be moved through a curved pathwhich is a horizontal projection of the path of the head. Means 'isprovided to modify the path of the dressing tool to compensate for sideclearance, undercut and spiral angle as may be desired. The spiral angleof a form tool is the equivalent of the helical angle at the pitch lineof the rotary cutter to be produced. In the form tool, this spiral angleis the angle ofinclination of the cutting face laterally of the tool.The undercut in a form tool is the angle of inclination of the cuttingface longitudinally of the tool. In the case of a rotary :cutter, theundercut is the angular offset of the cutting face from a radial planethrough the cutter axis. The form tool for cutting a rotary cutterhaving an undercut face, may itself have no undercut, but in suchinstance has a .form compensated for the undercut on the cutter to beproduced.

In each case of a spiral angle, an undercut, and/or a clearance angle,the effective contour .of the grinding wheel .on the work isforeshortsued in some respect. This foreshortening is compensated for.by so changing the contour of the grinding wheel that the foreshortenedor distorted form which is applied to the work will be the desired form.

In the illustrated embodiment, the tool holder '26 (Figs. 1 and 3) ismounted on a horizontal shaft 2? which is journaled on a slide 28supported on a swinging head or arm '29. The arm 29 is mounted swingablyupon a pivot '30 secured to :an uprising portion SI of the table 5. Theslide '28 is freely movable radially on the swinging arm or head 29, yetits movement is constrained to a vertical plane. These move- .ments maybe guided and controlled by means of theshaft Zfl.

The .means which operates through the shaft 21, for guiding :and :movingthe tool holder through the desired paths preferably includes a support32 slidable longitudinally on the table 6. A side clearance control base33 is pivoted on said support 32 and carries a frame 33 (see Figs. 3 andon which an annular member or barrel 34 is rotatably mounted on an axisinclined at the end clearance angle with the horizontal. A cross slide35 adjustably mounted within said barrel for movement transversely ofits axis carries a rotatably mounted sleeve 36. A shaft 31 is slidableaxially in the sleeve, but is suitably held against rotation relativethereto as by balls 3'1 operating in grooves 31'. A head, guide orradius bar 38 on one end of said shaft has a universal connection 39,preferably of a ball and socket type, with the shaft 21 on which thetool holder 26 is mounted.

To compensate for spiral angles and undercutting, the opposite end ofthe shaft 31 carries a second radius bar 40 having a universalconnection 4| with a slide 42 movable radially on a swinging control arm43 which is pivoted as by a pin 44 on an inclined aXis parallel to theshaft 31. The pin 44 is positioned in the upper end of an adjustablymounted spiral angle control member 45, which member is angularlyadjustable upon arcuate ways 46 (Figs. 3 and 5) about an axisperpendicular to the shaft 31. These ways are formed on an undercutcontrol member 41 which in turn is angularly adjustable about an axisperpendicular to the shaft 31 and to the axis of the Ways 46, on arcuateways 48 formed on a controlsupport 43 mounted on the end of the frame 33The support 32 is slidably supported, through antifriction elements 32upon the table 6 for movement transversely of the spindle 4. Thisprovides a freely slidable perpendicular connection between the guidingand compensating means and the tool holder 26 adapted to project, ontothe vertical plane of the tool holder, the curve through which theuniversal connection 39 is moved when positioned radially outward of theaxis of shaft 31 since the-connection is constrained to move in' a planeparallel to that of the tool holder. The side clearance control base 33is pivotally mounted on the support 32 by means of a pivot pin 50 and anannular way 5!. A protractor 52 (Fig. 5) determines the amount of sideclearance by the position of the base 33 and clamping bolts 53 securethe parts in an adjusted position.

The frame 33 has a segmental portion 33 mounted on an arcuate Way 33 onthe base 33, and comprises a U-shaped end portion (Fig. 5)

extending to the right in the drawings from the segmental portion. Thearcuate way 33 is concentric with the shaft 31.

The frame 33 also has arcuate ways 55 concentric with the shaft 31 andarranged to support and guide the barrel 34, the periphery of which isprovided with a corresponding guide 56. The periphery of the barrel alsohas worm wheel teeth 51 (Figs. 1 and a) engageable by a worm 57 on amanually operable shaft 58 rotatably mounted the base frame 33 The crossslide 35 is mounted on rectilinear ways 55 extending transversely of thebarrel so that the shaft 31 may be moved diametrically across thebarrel. A cross feed screw 30 (Figs. 1 and 3) is arranged to engage anut Bl on the cross slide manipulable through a squared end 62 foradjusting the cross slide transversely of the barrel,

The rotatable sleeve 33 is suitably secured against longitudinalmovement and may be rotated by means of a manually operable worm 63 on ashaft I53 (Figs. 1, 3 and 4) which engages a worm wheel 64 secured tothe sleeve and has squared outer ends 65. The sleeve may be locked inits normal position by means of a spring operated plunger 66.

The radius bars 38 and 43 are secured in a common longitudinal planethrough the axis of the shaft 31. The radius bar 38 has a slide it whichis adjustable radially thereon and secured by suitable clamping bolts H(Fig. 1). This slide it supports one member I2 of the universal joint 39and the other member 13 is secured to the tool holder shaft 21. Thestructure associated with the radius bar 40 may substantially duplicatethat just described. Thus, the radius bar 40 has a radially adjustableslide 14 secured by bolts 15. This slide carries one member 76 of theuniversal joint 4 I the other member ll being secured to a shaft 18rotatably mounted on the slide 42 carried by the swinging arm 43.

The various adjustments which have been described function severally orjointly to produce the movement of the dressing tool through such a pathrelative to the grinding wheel as will develop a required contour on thewheel. Since this contour may be variously modified, the work or toolblank holder B must be capable of adjustment to properly correlate therelationship of the tool blank with the grinding wheel. The new andimproved work holder which embodies the features of invention coveredherein includes adjustments whereby the work holder may be set quicklyand accurately to positions conforming to and initially determined bythe adjustments of the dressing tool.

Referring particularly to the structure of the work holder B, the worksupport 23 is slidably mounted on the uprising portion 3| of the table 5along ways 80 for movement transversely of the grinding wheel spindle 4so that after the grinding wheel W has been properly dressed, the toolblank holder B may be traversed across the grinding wheel without movingthe table. This traverse movement may be imparted to the work support 23manually by any suitable means, which means preferably includes a handwheel 8! rotatably mounted on the table portion 3| and readilyaccessible to an operator standing in front of the machine.

The work support B, as shown in Figs. 6 to 10, comprises a circular baseI00 rotatably mounted on the upper surface of the support 23 by means ofa pivot bolt HO and an annular guide ring Ill. The guide ring may beadjusted angularly with respect to the support 23 as indicated on ascale It)! and may be secured in its adjusted position by means of thepivot bolt. A spring pressed plunger or index pin H2 carried on the baseI30 is adapted to engage either one of two sockets H3 positioned apartin the ring I i I. Extending upwardly from the base i953 and formedintegrally therewith are a pair of inclined brackets H4. A body memberH5 is positioned intermediate said brackets and pivotally mounted on ahorizontal shaft I04 mounted in the brackets. The pivotal mounting isprovided for permitting modification of the end clearance angle to whichthe tool blank 25 is ground, the upper portion of the member I 15carrying clamping bolts IE6 passing through slots Ill in the brackets H4to secure the body member in its adjusted position as determined by ascale H8.

A centrally apertured disk us is secured to the body member H5 and isprovided with an annular T-slot I and a central boss I2I. An angularlyadjustable member or head I22 has a shoulder engaging said boss andcarries a plurality of bolts I23 with their heads in said T-slot so thatthe head I22 may be clamped in its adjusted position on the disk II9 asdetermined by an indicating scale N52. The head I22 is provided withrectilinear guides I23 normally positioned horizontally and carrying across slide I24 having corresponding ways I25. A somewhat circular toolblank supporting member E26 is angularly adjustable on the cross slideI24, being positioned thereon by means of a boss I21 on the cross slideand being adapted to be clamped in its adjusted position, as determinedby a scale I63, by means of a plurality of bolts I23. Suitable means,such for example as a notch I29 and clamping bolt I39, may be providedfor securing the tool blank to the supporting member H6.

The cross slide I24 may be adjusted on the guides I23 to displace thetool blank longitudinally of the grinding spindle 4 by means of a feedscrew i3I (Fig. 9) non-rotatably supported on the cross slide andengaged by a nut I32 rotatably mounted on the head I22. This nut has abevel pinion I 33 thereon engaging a second bevel pinion I34 mounted onone end of a shaft I35. A Worm wheel I36 on the shaft I is driven by aWorm 53'! on the shaft Ili l to move the cross slide.

The shaft I35 preferably extends outwardly of the body member H5 tooperate a micrometer device designated generally I38 by which theposition of the cross slide may be indicated. The amount of thedisplacement of the tool blank by movement of the cross slide may bedetermined by the difference between the two readings on the micrometerdevice I38.

-As described hereinbefore, the dressing mechanism A and the tool blankor work holder B are generally constructed at a standard or desired endclearance angle, the dressing mechanism being so set to compensate forthe modified form required on the grinding wheel because of the endclearance angle, and the work holder being so set to insure grinding ofthe tools to the desired clearance angle. Form cutters of the straightgash type are the simplest for which to grind form tools. The setup ofthe machine for grinding form tools for this type of cutter willtherefore be described first.

The setup of the tool blank is particularly simple as the work holder,with the protractors indicating zero, holds the tool blank parallel tothe table 6 and perpendicular to the grinding wheel spindle. Thedressing mechanism is also set at zero except to the angle of form.Thus, the protractors 90, ill and 92 on the side clearance, spiral angleand undercutting controls respectively are at zero and the slides Hi andM are central of the radius bars 38 and All respectively, as illustratedherein. The dressing fixture is set to the desired angle of form byrotating the barrel 34. With the dressing tool in the vertical planethrough the axis of the wheel W, feeding movement of the dressing toolmay be accomplished by actuating the cross slide 35, the head 3 beinglowered to cause the tool to engage the wheel. Following the dressingoperation, the work holder is moved through a working stroke relative tothe grinding wheel and the form, which has been set up by theadjustments of the dressing device, is produced on the work blank.

For straight gash cutters with undercut faces, the setting of thedressing mechanism is the same except that the undercut control member47 is set at an angle of negative rake. The negative rake referred to isnot the undercut angle on the cutter but is the angle to which it isnecessary to dress the grinding Wheel to give the proper foreshorteningon the form tool. The angle is a function of the undercut angle on thecutter, the clearance angle on the form tool, the clearance angle on thecutter tooth and the diameter of the cutter. An empirical equation canreadily be set up and by means of a simple calculation, the proper anglefor setting the undercut angle control member ll may be obtained.

For grinding a straight gash cutter form tool with side clearance, thework holder is adjusted so that the tool blank is set at an angle otherthan the standard clearance angle depending upon the angle of sideclearance. Thus, the head I26 is set at a slight angle to the verticalabout the inclined axis of the work holder, this angle corresponding tothe angle of side clearance. The tool blank is also swung horizontallyat a suflicient angle on the scale IilI to give the proper sideclearance angle. The form dressed upon the grinding wheel is the same asfor straight gash cutters, the position of the tool blank while beingground making provision for obtaining the desired shape on the face ofthe tool.

In order to grind form tools for straight gash cutters having both sideclearance and undercut faces, the tool blank is set the same as forgrinding form tools with side clearance and the dressing fixture is setthe same as for dressing grinding Wheels for cutters with undercutfaces. This combination dressing of the grinding wheel for undercut andpositioning the tool blank for side clearance produces a form tool, theface of which is correct for cutting this type of cutter.

To grind tools for spiral gash cutters, the tool blank is set at thestandard end clearance angle with the protractors oi the Work holder setat zero. The head 1255 is set at the tip angle corresponding to theclearance and gash angles. In the dressing mechanism, the spiral controlmember i5 is set at the angle of the required gash. Since the head I26is tipped, the tool blank is brought to the proper height to compensatefor the spiral gash.

When grinding tools for spiral gash cutters with undercut faces the toolblank is set as for spiral gash cutter tools as just described. Thedressing mechanism, in addition to having the spiral control member i5set as just described, also has the undercut control member 41 set atthe required angle of negative rake.

In grinding form tools for spiral gash cutters with side clearance, thehead i26 of the tool holder is set at an angle to the vertical dependingupon whether right or left hand spiral gash as well as whether right orleft hand side clearance is desired, after which the tool blank is swunghorizontally about the pivot lid through the angle corresponding to therequired side clearance angle. The dressing mechanism is then swiveledon its pivot 59 so that the axis of the barrel 3% is perpendicular tothe back of the tool blank and the spiral control member 45 is setparallel with the face of the tool blank, the angle of which will beeither the combined angles of spiral and side clearance or theirdifference.

For grinding form tools for spiral gash cutters with both undercut facesand side clearances, the

tool blank is set as described for form tools for spiral gash cutterswith side clearance. The dressing mechanism is set as described, and.with the undercut control member 41 set at the proper angle.

In producing some form tools, combinations of the foregoing settingswill be necessary but in each instance the work holder may be accuratelyadjusted for coaction with a grinding wheel having a contour determinedby the adjustment of the dressing device.

I claim as my invention:

1. A work holder of the character described comprising, in combination,a support, an annular ring adjustable angularly on said support, a basepivotally mounted on said support guided by said ring, a pair ofbrackets inclined upwardly from said base, a body member mounted on ahorizontal shaft extending through said brackets for limited swingingmovement from a normal clearance angle inclination, a head angularlyadjustable on said body member about its inclined axis, a cross slide onsaid head movable transversely of said axis, and a tool blank supportingmember rotatably mounted on said slide,

2. A work holder of the character described comprising, in combination,a support, a base pivotally mounted on said support about a verticalaxis, bracket means inclined upwardly from said base, a body membermounted on a horizontal shaft supported by said bracket means forlimited swinging movement from a normal clearance angle inclination, across slide carried by said body member movable transversely of saidaxis, and a tool blank supporting member rotatably mounted on saidslide.

3. A work holder of the character described comprising, in combination,a support, a base pivotally mounted on said support, a pair of bracketsinclined upwardly from said base, a body member mounted on a horizontalshaft extending through said brackets for limited swinging movement, ahead angularly adjustable on said body member about an axisperpendicular to said shaft, a cross slide movable diametrically on saidhead, and a tool blank supporting member adjustably mounted on saidslide.

4. A work holder for a machine having a grinding wheel which is dressedto a modified form including a compensation for one or more of suchfactors as side clearance, end clearance, spiral angle and undercut,said work holder having, in combination, a reciprocable support, andmeans for mounting a Work blank on said support including a supportingmember for adjusting said work blank to a predetermined angle of endclearance inclination, and adjustable means for varying the position ofsaid blank rotatably and transversely with respect to the plane of theangle of inclination as required by the presence of compensation forsaid factors in the form of the grinding wheel.

5. A work holder for a machine having a grinding wheel which is dressedto a modified form including a compensation for one or more of suchfactors as side clearance, end clearance, spiral angle and undercut,said Work holder having, in combination, a reciprocable support, meansfor mounting a work blank on said support including a member forsupporting said work blank at an angle of end clearance inclination, andmeans movable on a plane paralleling the angular plane of end clearanceinclination for adjusting said work blank in a direction generallytransverse horizontally of the line of support reciprocation and in theplane of the angular position of the work blank.

6. A Work holder for a machine having a grinding wheel which is dressedto a modified form including a compensation for one or more of suchfactors as side clearance, end clearance, spiral angle and undercut,said work holder having, in combination, a reciprocable support, meansfor mounting a work blank on said support including a member forsupporting said work blank at an angle of end clearance inclination, andmeans for adjusting said work blank rotatably and horizontally in itsangular plane.

'7. A work holder for a machine having a grinding wheel which is dressedto a modified form including a compensation for one or more of suchfactors as side clearance, end clearance, spiral angle and undercut,said work holder having, in combination, a reciprocable support, meansfor mounting a work blank on said support including a member forsupporting said work blank at an angle of end clearance inclination,means for adjusting the work supporting means rotatably about a verticalaxis, means for adjusting the work blank horizontally in a directiontransverse of the line of support reciprocation, and means for adjustingthe work blank rotatably in the plane of its angular position.

8. A work holder of the character described comprising, in combination,a support, a .base pivotally mounted on said support about a verticalaxis, a body member mounted on said base for relative pivotal movementon a horizontal axis to provide limited swinging movement from a normalclearance angle inclination, a cross slide carried by said body member,and a tool blank supporting member adjustably mounted on said slide.

9. A work holder of the character described comprising, in combination,a base, bracket means extending upwardly from said base, a body member,a shaft pivotally supporting said body member on said bracket means forlimited swinging movement from a normal clearance angle inclination, andadjustable tool supporting means including a cross slide on said bodymember, and driving means interposed between said shaft and said crossslide for effecting reciprocatory adjustment of said cross slide.

10. A work holder for a machine having a grinding wheel which is dressedto a modified form including a compensation for one or more of suchfactors as side clearance, end clearance spiral angle and undercut, saidwork holder having, in combination, a reciprocable support, and meansfor mounting a work blank on said support including adjustable means forfixing the position of the face of the work blank to be ground at apredetermined angle of inclination with respect to said support and foreffecting rotational and rectilinear adjustment of the position of saidtool blank with respect to the angle of inclination.

JOHN EDGAR.

